Efficience d’un système bâti sur le TRS global par poursuite du diagramme de fiabilité

The efficiency of the system built in the global OEE per pursuit of the Reliability Block DiagramThe OEE (Overall Equipment Effectiveness) has become across the NFE 60-182 norm, one of the major performance indicator of the efficiency of the production systems. It integrates essentially three notions (Quality, Availability, and Performance) depended in internal of the reliability and the maintenance logistic. If the evaluation of one element’s OEE can be easy,  his expression for a complex system is too difficult (the taking into account of redundancies, of temporal scale’s factors, of desynchronization, …). The use of the functional synchronized approach can bring solutions comparable to the block diagram reliability. We present in this paper a method of evaluation of the efficiency and the procedures of calculation of the OEE based in the global structure of systems (series and parallels) and the objectives of production (nominal and degraded)

Burrows-Wheeler text compression with fountain codes

This paper presents an algorithm in a purely lossless text compression setting based on fountain codes and the Burrows-Wheeler transform (BWT). The scheme consists of five stages, each of which is briefly described in the paper. The algorithm offers encouraging compression rate performance for large files. A summary of the results of the proposed scheme and other compression schemes is provided

Stability of one and two-dimensional spatial solitons in a cubic-quintic-septimal nonlinear Schrodinger equation with fourth-order diffraction and PT-symmetric potentials

In this paper, the existence and stability of solitons in parity-time (PT)-symmetric optical media characterized by a generic complex hyperbolic refractive index distribution with fourth-order diffraction (FOD) coefficient and higher-order nonlinearities have been investigated. For the linear case, we have demonstrated numerically that, the FOD parameter can alter the PT-breaking points. Exact analytical expressions of the localized modes are obtained respectively, in one and two dimensional nonlinear Schrodinger (NLS) equation with both self-focusing and self-defocusing Kerr, and higher-order nonlinearities for nonlinear case. The effects of both FOD and higher-order nonlinearities on the stability/instability structure of these localized modes have also been discussed with the help of linear stability analysis followed by the direct numerical simulation of the governing equation. Some stable and unstable solutions have been given and, it has been seen how higher-order self-focusing and self-defocusing nonlinearities can influence the stability/instability of the system. (C) 2021 Elsevier B.V. All rights reserved

Constraints of micro hydroelectric power plants in the west region of Cameroon

The objective of the present work is to study the constraints of Micro Hydroelectric Power Plants (MHPPs) installed in the West Region of Cameroon. The study was carried out between January 2005 and December 2008 and is related to water conveyance structures, production facilities; transportation and distribution networks, management and maintenance of the MHPPs. Data were collected using questionnaires, direct interviews and site observations and measurements. The main results show that the poor working condition on 60% of power plants is due to lack of previous survey before setting up the facility. Deteriorations and silting up of structures exist on all sites and  result from their poormaintenance. Machine vibrations and bad weather also contribute to the deteriorations. On 50% of the sites, water conduits of diversion works consist of low pressure pipes which break down very often. On 80% of sites, power houses are single narrow rooms that house the machinery. On 80% of sites, the current produced is single phase and the power is lower than the demand of the population. On the transportation and distribution networks, electric conductors on 43% of sites are within reach ofinhabitants. On 80% of sites, grounding and neutral wires do not exist or are poorly installed. For maintenance and repairs, problems exist on all sites because of the lack of spare parts, the lack of capable technicians and poor management of funds